Without limiting the scope of the invention, its background is described in connection with the manufacturing of bipolar transistors, as an example.
Heretofore, in this field, in bipolar mesa transistors, the base layer extends outside the area of the active device region to enable contacting of the base. This area is called the extrinsic base region, outside the active device region, and it increases the junction capacitance between the base layer and the layer beneath the base (e.g. the collector, in emitter-up devices).
Since junction capacitance limits the high-frequency performance of bipolar transistors, great effort has been spent on reducing the junction capacitance between the base layer and the layer beneath the base. Accordingly, improvements which overcome any or all of the problems are presently desirable.